1. Field of the Invention
The invention relates to an easy-to-use, accurate wideband IC device modeling method that will be beneficial to enhancing the design reliability of high-speed IC's and switching-type high-frequency IC's. The method is based on time-domain ultra short impulse responses measurement and subsequent model elements extraction.
2. Description of the Prior Art
To accurately simulate the performance of high-speed IC's and switching-type high-frequency IC's, accurate wideband device models for both passive and active semiconductor devices are essential, especially when the data rate enters into >Gbps range for high-speed IC's or when the (large-signal) oscillation frequency is of GHz and above. For active devices, however, current commonly used device models such as BSIM3V3 models do not properly cover the high-frequency behavior of devices. Conventional extension models based on the BSIM3V3 models and frequency-domain S-parameter fittings can only cover up to some GHz bandwidth, and the accuracy has been poor. It is not easy to establish good wideband (tens or even hundreds of GHz) device models by frequency-domain characterizations and corresponding fittings. Proper proposition of equivalent circuit models is critical in achieving a good fit to the measured S parameters. In fact, it is very difficult to fit all the S parameters in a wide frequency range. Therefore, the narrow-band models thus generated and their fitted “wideband” models cannot correctly describe the nonlinear and frequency-dependent characteristics of the devices. (These characteristics are essential to the ultra-short time-domain (TD) responses of the devices and are important for designing high-speed circuits.) That is, these models are not very suitable for the use in switching type circuits where wideband signals are present.
The inventor has notice the various disadvantages associated with the conventional wideband device models and thought to improve it, and after having carried out an intensive study for many years, has successfully developed a wideband device modeling method of the invention.